Endless abrasive belt and method of manufacturing same



D. s. GROVE ENDLESS ABRASIVE BELT AND METHOD OF MANUFACTURING SAME! March 25, 1952 Filed April 8, 1949 ATTORNEYS.

I N V EN TOR. flow 51 6W0 ME,

Patented Mar. 25, 1952 ENDLESS ABRASIVE BELT AND METHOD OF MANUFACTURING SAME Don S. Grove, Carnegie, Pa.

Application April 8, 1949, Serial No. 86,184

12 Claims.

This invention relates to an endless abrasive belt and methods for manufacturing the same. While belts according to my invention are of general utility, they have been developed particularly for use in the grinding of steel strip, sheets and bars, preliminary to coiling the strip into coils, or finishing operations on sheets and bars. Heretofore, in the grinding and polishing of coils, sheets and bars the abrasive belts used have been of paper. Paper belts, however, are subject to many disadvantages in connection with their use for grinding of steel strip, sheets and bars. In the grinding of strip, sheets and barsv a tremendous amount of heat is generated and the temperature of the belt may reach 250 F. or more at the point of contact. This high heat has a deleterious effect on paper belts, in that it causes separation of the paper plies which are secured together with a glutinous adhesive which softens and fails under the influence of heat and continuous flexing. Furthermore, paper belts are adversely affected by various of the polishing oils which are presently used as lubricants, and which weaken the splice and fibers of the paper. Paper belts are, of course, hygroscopic, and are subject to changes in atmospheric conditions so that the length of the belt changes with atmospheric conditions. The expansion and contraction with changes in relative humidity cause breakage of the paper and reduce the effectiveness of the adhesive used to secure the abrasive grains to the belt.

In paper belts, if there happens to be a line burr along the edge of the strip, sheet or bar, resulting from a slitting or shearing operation, instead of the abrasive belt grinding down the burr, the burr will most often cut the paper, and as soon as the paper is torn it is useless and the belt must be scrapped. The same result will follow from strip, sheets or bars having cracked edges, or the like. The changing of belts in mid-coil necessitates stopping the entire production line, while belts are being changed, and the change time has been found to be unduly high.

It has been found that strip, sheet and bar stock characterized by camber, cross-bar or a buckled condition, cannot be ground with paper belts because the excessive, highly localized pressuresc'ause the belt to break, tear or wrinkle, so that it has to be scrapped. For these reasons the replacement cost of belts has been unnecessarily high and of course has resulted in a higher cost per ton of finished material.

With the foregoing considerations in mind it is an object of my invention to provide a belt which will be of greatly increased strength, and

which will therefore not disintegrate by reason of having to grind down burrs or rough edges on the strip, sheet or bars.

-It is another object of my invention to provide a belt which is completely moistureproof, so that it will not be affected by atmospheric conditions.

It is still another object of my invention to provide a belt of such durability that when the abrasive material is worn down the belt can-be recoated and re-used numerous times, say, as

many as 600 times.

It is yet another object of my invention to provide a belt which will be of constant thickness throughout its length whereby the quality of the ground and polished strip, sheet or bars, will be enhanced.

A further object of my invention resides in the provision of a belt for fine finishing operations, which will operate without chatter. I have found that chatter is caused by a hinging action at the belt joint, and therefore this object of my invention involves the provision of a helically wound belt, whereby chatter is eliminated.

Another object of my invention involves the provision of a method for manufacturing a belt as outlined above whereby other of the objects discussed above are achieved. This last mentioned object includes the object of providing a new method of applying abrasive grains to the belt in a manner which will render the belt'more satisfactory, and give it a longer useful life for each coating.

These and other objects of the invention which will become apparentto one familiar with the art upon study of these specifications, I accomplish by that certain construction and arrangement of parts, and by that series of method steps, of which I shall now disclose exemplary embodiments.

Reference is made to the drawings forming a part hereof, and in which: 7

Figure 1 is a fragmentary plan viewof a belt according to my invention with parts broken away;

Figure 2 is a longitudinal cross-sectional view of the same with the plies separated in part to show the construction;

Figure 3 is a side elevational view of a machine suitable for the application of the" abrasive coating;

Figure 4 is a plan view of the same taken on the line 44 of Figure 3;

Figure 5 is a fragmentary cross-sectional view on a greatly enlarged scale of a finished belt,

and

of another way in which belts may be assembled.

The belt according to my invention is of two or more plies. The plies themselves are of textile material preferably of a material chosen from the group consisting of cotton rayon, nylon and ramie. This textile material will have a weight per square yard between three ounces and thirty eight ounces, or even more. The particular weight of material is selected to meet the particular conditions as to light or heavy duty to which the belt is to be subjected.

That ply which is to be the outside in the finished belt is coated on its underside with an elastomer. This elastomer may be that known as Neoprene, which is made by polymerizing chlorobutadiene under pressure. All the remaining plies are impregnated with an elastomer such as Neoprene by being immersed in the elastomer and having the excess material knifed off. The weight of the drying solids based on the weight of the textile material will be in the range from about 40% to about 95%, but preferably in the vicinity of 70%. After impregnation and coating the plies are dried to drive 01f the solvent in the impregnating material by being drawn through a heated chamber at a temperature cf about 200 F. It will be observed from the foregoing that all the plies but one are impregnated with the elastomer, while the one ply is coated on one side only with the elastomer. The uncoated side of said one ply will be the side to which the abrasive grains are applied in the finished belt.

The various plies are then passed over a steam heated table. or the like, o soften the ela-tomer with which they are coated or impregnated. The plies are plied toget er and adhesively bonded to each other with a latex adhesive in such manner that the untreaed sides of said one plv is on the outside. The laminated plies are then calendered to stretch and finish the belt. The calendered belt is then vulcanized in a rlaten pre-s or the like at a pr ssure of about 2.000 pounds ner squire inch and at a temperature of about 325 F.

A belt assembled as described above will have its plies thoroughly and tightly bonded to each other, and- I have determin d that the adhesive strength between plies will be between 40 and 55 pounds per sq are inch per ply after the belt has been permitted to cool.

It will be understood that up to this oint the plies have been treated in consderable width. At this stage of the process the belt e ges are cut square to the desired width of the finished belt, and the cut edges have then applied to them an elastomer to protect them and to seal them. This elastomer may again be Neoprene and y, if desired, be pigmented.

The belt treated as above described is then cut to the desired length. The ends of the belt, are

cut so that the ends of the plies are stepped and so that the ends of the plies are on a bias angle to the: belt edge; In this way, wheri tl i belt is finally assembled into endless form the b1as ends of the individual plies are in abutting relation with the butt joints of the respective plies 1n stepped relation lengthwise of the belt. This construction may be understood with reference to Figures 1 and 2 in which the respective plies are indicated at l0, Hand 12. The solid line at l-3 indicates the butt joint between the two ends of the ply Ill. The butt joint between; the plies H is indicated by the broken line at HE and the butt joint between the ends of the ply li is indicated by the broken line i5. As seen in Figure 2, the ply l5 and the ply id have been impregnated with the elastomer, while the ply I0 has only been coatedon its under side with the elastomer. Each of the inner surfaces of the plies has been coated with the latex adhesive as indicated at 16, and the upper surface of the ply I0 is untreated.

The joint as described above is then again vulcanized in a lap press having steam heated platens at a temperature of about 325 F. In this way a smooth even joint of constant thickness is insured.

I have indicated more or less diagrammatically in Figure 6, another way in which the plies y be assembled. As there shown, one ply comprising a long strip of relatively narrow material is wound spirally upon a mandrel, as indicated by the broken lines H. The outer ply of similar material is wound over the plies I! in the opposite direction, as indicated by the solid lines I8. The plies themselves will have been treated as described above. When a belt has been assembled according to Figure 6 it may be removedfrom the mandrel and used in its then form. If desired, of course, a belt of considerable width may be manufactured according to the diagram of Figure 6, and the belt may then be slit into desired widths.

The belt is now ready for the application of the abrasive grains. The abrasive material used may be aluminum oxide. grains, silicon carbide grains, garnet, emery, or any other suitable abrasive grains. The machine shown in Figures 3 and 4 is somewhat diagrammatic, but it comprises, for example. two fixed rolls [9 and 20 over which the belt passes, one of which rolls may be driven, as indicated by the belt and pulley 2| seen in Figure 4. A third roll 22 is preferably pro ided on a pivoted arm 23 so that the tensiorron the belt may be adjusted, and also to facilitate placing the belt on the machine and removing it'- from the machine. The various pulleys are suita ly mounted on a frame indicated generally at 24, and between the pulleys l9 and 20 a supporting plate 25 is provided.

The adhesive is applied to the belt by means of a hopper 28 having a spout 21. The snout 27 of course extends entirely across the width of the belt to be treated, and conventional means for controlling the flow of adhesive from the hopper may be provided. The thickness of the adhesive coating, and its thorough distribution (particularly where a previously used belt having residual grains on its surface is to be recoated, and where it is important that the adhesive enters into the interstices between grains) are insured by the calender roll 27a, and the excess adhesive is scraped off by a doctor blade 21b. The calender roll 21a should be quite soft to accomplish the purpose, and therefore an elastomer such as Neoprene of 25 Durometer hardness is about the hardest that can be used. It is much preferred to use an elastomer such as Neoprene of about 15 Durometer hardness. Means (not shown) are provided for imparting to theicalender roll 21a a reciprocatin movement transversely of the belt, as well as an oscillating movement in a plane parallel to the belt. The adhesive is preferably of the sodium silicate type, but it may be magnesium oxychloride, or other suitable adhesive. While the adhesive is being :applied' I prefer to drive the belt, which in Figures 3 and 4 is indicated at 28, at about 20 feet per minute in the direction shown by the arrows.

As soon as the entire belt has been coated I prefer to step the speed of the belt up to about 32 feet per minute for the application of the abrasive grains. The abrasive grains are applied by means of a nozzle indicated generally at 29, the abrasive grains being supplied from a suitable hopper through the tubes 30. Air is supplied through a tube 3| at a pressure of about 13 pounds per square inch above atmospheric pressure.

I have found that the best results are obtained if the nozzle is directed radially at a point where the belt is traveling around one of the rolls, and preferably bisects the angle between the surfaces of the belt approaching and leaving the roll. I also find that it is preferable and that the best results are obtained when the end of the nozzle is about 14 inches from the strip surface. I prefer to apply as much grain as the adhesive will hold, and therefore I prefer to let the belt make three complete revolution-s. When the blast for the adhesive is shut off I apply to the surface of the belt a star roller indicated at 32 which is mounted on a pivoted arm 33. This star roller serves to pop off the excess abrasive grain.

The belt with its coating is then removed from the machine and is permitted to dry. In order to prevent the belt from drying in relatively large areas which would tend. to make the belt stiff, I prefer to conduct the drying operation by hanging the belt over a slowly rotating roller, so that during the drying period the belt is simplyloosely rolled along so that the adhesive bond between the coating of abrasive grains and the belt is .broken up into a very large number of small bonds. Thus, the finished belt retains substantially its original flexibility and abrasive grains will not pop off when it is flexed. I

I have found that with a belt made according to the procedures outlined herein the life of the belt is greatly increased, and over a period of time 30% less close down time for changing belts has been found. Since the inner surface of the belt which rides on the rollers in the grinding machine is impregnated with the elastomer, better driving friction is obtained, so t at constant operating speed of the belt and higher production result. I have found that a reduction in the down time, and reduction of belt breakage whereby changing of belts in mid-coil is eliminated, results in a consistent finish from end to end of the coil. This makes the coil more saleable. as well as reducing the cost thereof. In actual production runs I have noted cost reductions as high as $12 00 per ton when using belts according to the present inven ion, when compared with the use of conventional paper belts, and an average cost reduction of $3.80 per ton has been achieved. 5

It will be clear that various modifications ma be made without departing from the spirit of my invention, and therefore I do not intend to limit myself to all of the precise details mentioned herein. What I do claim to have invented is set forth in the claims which follow:

l. The method of making a plied endless abraa one ply on the outside, calendering said plies and vulcanizing them under apressure of about 2000 pounds per square inch at a temperature of about 325 F., cutting said plies to the desired belt width, applying an elastomer to the plied edges of said belt, joining the free ends of said belt with the respective ply ends in bias butting relation and with the butt joints in the respective plies in stepped relation lengthwise of said belt with the untreated side of said one ply on the outside, and vulcanizing said joint at a temperature of about 325 F., causing said belt to pass over rollers, coating said belt with an adhesive on its untreated side, and blowing abrasive grains onto said adhesive by means of a nozzle, with a pressure of about 13 pounds per square inch, the blast of said nozzle being directed substantially radially of one of said rollfers, and with said nozzle being at a distance of about 14 inches from the belt surface.

2. The method of making plied endless abrasive belt, which includes the steps of preparing one ply by coating one side thereof with an elastomer, preparing at least one additional ply by impregnating the same with an elastomer, driving off the solvent in said elastomer by-heating said plies to a temperature of about 200 F., softening said elastomer by heating said plies, and adhesively securing said plies together by a latex adhesive with the untreated side of said one ply on the outside, calendering said plies and vulcanizing them under a pressure of about 2000 pounds per square inch at a temperature of about 325 F., cutting said plies to the desiredbelt width, applying an elastomer to the plied edges of said belt, joining the free ends of saidbelt with the respective ply ends in bias butting relation and with the butt joints in the respective plies in stepped relation lengthwise of said belt, with the untreated side of said one ply onthe outside, and vulcanizing said joint at a temperature of about 325 F'., causing said belt to pass over rollers, coating said belt with anadwith-a pressure of about 13 pounds per square inch; the blast of said nozzle being directed suban adhesive on one side, and blowing abrasive grains .onto said adhesive by means of a nozzle, said nozzle being directed substantially radially of one of said rollers.

4. The method of making an endless abrasive belt, which includes the steps of causing said belt .to pass over rollers, coating said belt with an adhesive. on one side, and blowing abrasive grains onto, said adhesive by means of a nozzle, said .nozzle being directed substantially radially of .one of said rollers and drying said belt by causingit to hang freely over a slowly rotating roll, whereby to break up the adhesive bond between said coating of abrasive grains and said belt into small increments.

5. The method of making an endless abrasive belt, which includes the steps of causing said belt to pass over rollers, coating said belt with an adhesive on one side, and blowing abrasive grains onto said adhesive by means of a nozzle, with a pressure of about thirteen pounds per square inch, the blast of said nozzle being directed substantially radially of one of said rollers, and with said nozzle being at a distance of about fourteen inches from the belt surface.

6. The method of making an endless abrasive belt, which includes the steps of causing said belt to pass over rollers, coating said belt with an adhesive on one side, and blowing abrasive grains onto said adhesive by means of a nozzle, with a pressure of about thirteen pounds per square inch, the blast of said nozzle being directed substantially radially of one of said rollers, and with said nozzle being at a distance of about fourteen. inches from the belt surface and drying said belt by causing it to hang freely over a slowly rotating roll, whereby to break up the adhesive bond between said coating of abrasive grains and said belt into small increments.

7. The method of making a plied endless abrasive belt, which includes the steps of impregnating a long, relatively narrow strip of textile material with an elastomer and winding it helically upon a mandrel to constitute a ply, coating said ply with a latex adhesive, adding at least one additional ply by coating another long, relatively narrow strip of textile material on one side with an elastomer and winding it helically upon said coated ply in the opposite direction and with the untreated side of said other strip outwardly, to constitute an additional ply, removing said plied belts from said mandrel, calendering said plies, and vulcanizing them.

8. The method of making a plied endless abrasive belt, which includes the steps of impregnating a long, relatively narrow strip of textile material with an elastomer and winding it helically upon a mandrel to constitute a ply, coating said ply with a latex adhesive, adding at least one additional ply by coating another long, relatively narrow strip of textile material on one side with an elastomer and winding it helically upon said coated ply in the opposite direction and with the untreated side of said other strip optwardly, to constitute an additional ply, removing said plied belts from said mandrel, calendering said plies, and vulcanizing them and slitting said plied belts into desired finished belt width.

9. The method of making a plied endless abrasive belt, which includes the steps of preparing a belt by coating one ply on one side with an elastomer, impregnating at least one additional ply with an elastomer, adhesively securing said plies together by a latex adhesive with the untreatedside of the first mentioned ply on the outside, causing said belt to pass over the rollers, coating said untreated side with an adhesive, and blowing abrasive grains onto said adhesive by means of a nozzle, said nozzle being directed substantially radially of one of said rollers.

10. The method of making a plied endless abrasive belt, which includes the steps of preparing a belt by coating one ply on one side with an, elastomer, impregnating at least one additional ply with an elastomer, adhesively securing said plies together by a latex adhesive with the untreated side of the first mentioned ply on the outside, causing said belt to pass over the rollers,

8 coating said untreated side with an adhesive, and blowing abrasive grains onto said adhesive by means of a nozzle, said nozzle being directed substantially radially of one of said rollers, and drying .said belt by causing it to hang freely over a slowly rotating roll, whereby to break up the adhesive bond between said coating of abrasive grains and said belt into small increments.

11. The method of making a plied endless abrasive belt, which includes the steps of preparing a belt by coating one ply on one side with an elastomer, impregnating at least one additional ply with an elastomer, adhesively securing said plies together by a latex adhesive with the untreated side of the first mentioned ply on the outside, causing said belt to pass over rollers, coating said untreated side with an adhesive and blowing abrasive grains onto said adhesive by means of a nozzle, with a pressure of about thirteen pounds per square inch, the blast of said nozzle being directed substantially radially of one of said rollers, and with said nozzle being at a distance of about fourteen inches from the belt surface, and drying said belt by causing it to hang freely over a slowly rotating roll, whereby to break up the adhesive bond between said coating of abrasive grains and said belt into small increments.

12. The method of making a plied endless abrasive belt, which includes the steps of preparing a belt by coating one ply on one side with an elastomer, impregnating at least one additional ply with an elastomer, adhesive securing said plies together by a latex adhesive with the untreated side of the first mentioned ply on the outside, causing said belt to pass over rollers, coating said untreated side with an adhesive, and blowing abrasive grains onto said adhesiveby means of a, nozzle, with 'a pressure of about thirteen pounds per square inch, the blast of said nozzle being directed substantially radially of one of said rollers, and with said nozzle being at'a distance of about fourteen inches from the belt REFERENCES CITED The following references are of record file of this patent:

UNITED STATES PATENTS in the Number Name Date 1,929,839 Dawson, Jr Oct. '10, 1933 2,004,479 Merrill June 11, 1935 2,038,782 Ellis Apr. 28, 1936 2,059,583 Jackson et al. Nov. 3, 1936 2,071,563 Newcomb et al Feb. 23, 1937 2,137,305 Perazzoli Nov. 22, 1938 2,141,658 Melton et a1 Dec. 27, 1938 2,219,853 Tone Oct. 29, 1940 2,226,553 Cross Dec. 31, 1940 2,335,902 Ball et a1 Dec. 7, 1943 2,357,823 Hatch et al Sept. 12, 1944 2,441,970 Lesesne May 25, 1948 FOREIGN PATENTS Number Country Date. 20,668 Great Britain Sept. 19, 1911 451,331 Great Britain Aug. 4, 1936 

